What are the roles of antioxidants in human body?

Antioxidants are natural compounds found in foods that help protect the body from armful free radicals.

The researches show that human diseases are mediated by oxidative stress and imbalance between pro-oxidant and antioxidant factors. The human body has several mechanisms to counteract oxidative stress produced in situ, or be externally supplied by food and/or supplements.

The majority of the available research on the role of antioxidant has focus on vitamin E. Vitamin E is the major antioxidant in the lipid environment of cellular and subcellular membranes, and also in plasma lipoproteins, protecting the vital phospholipids from peroxidation.

The vitamin, chiefly α-tocopherol, is specifically and actively incorporated within biological membranes where it stabilizes the lipoprotein structure.
What are the roles of antioxidants in human body